Dynamo-electric machines



p 1967 L. J. WOODMAN 3,340,414

' DYNAMO-ELEGTRIC MACHINES Filed Aug. 17, 1965 United States Patent 3,340,414 DYNAMO-ELECTRIC MACHINES Leonard James Woodman, London, England, assignor to C.A.V. Limited, London, England Filed Aug. 17, 1965, Ser. No. 480,304 2 Claims. (Cl. 310-194) ABSTRACT OF THE DISCLOSURE This invention relates to dynamo-electric machines of the kind wherein field coils are mounted about the stems of substantially T-shaped pole pieces between the head portions of the pole pieces (which serve as the pole tips) and a yoke to which the foot of the stem portions are secured.

The object of the invention is to provide in such machines convenient means for insulating the field coils electrically from the pole pieces and yoke.

According to the invention means for insulating the field coil electrically from a pole piece and yoke of a dynamo-electric machine of the kind specified comprises a preformed ring of insulating material having a channelshaped cross-section embracing the coil with the base portion of the ring disposed against the head portion of the pole piece and the walls of the ring extending towards the yoke, and a preformed apertured shield of insulating material lying against the internal periphery of the yoke to close the open side of the channel of the ring.

The objects will be apparent from the accompanying drawings in which:

FIGURE 1 is a cross sectional view of the stator of one example of a dynamo-electric machine to which the invention may be applied, and

FIGURE 2 is a fragmentary view illustrating a modified form of the shield for cooperation with the channelshaped ring of insulating material.

Referring to FIGURE 1 there is provided a substantially cylindrical casing 1 which constitutes the yoke of the stator of a dynamo-electric machine. Secured to the Patented Sept. 5, 1967 casing in known manner are the ends respectively of the stems, 3 of a pair of pole pieces 2 that are substantially T-shaped in cross sections. The pole pieces extend inwardly from the casing so that their heads 4 constitute pole tips which are presented to the rotor (not shown) of the machine. Moreover, the inner surface of the heads of the pole pieces are shaped to cylindrical form having an arc of curvature struck from the axis of rotation of the rotor. The stems 3 of the pole pieces are surrounded respectively by the field coils 5 of the machine, these field coils being disposed between the outer sides of the heads 4 of the pole pieces and the casing 1.

In order to insulate the field coil from its pole piece and the casing each coil is enclosed within a preformed ring 6 of insulating material having a channel-shaped cross section, and disposed with the base 6' of the channel against the outer side Oif the head 4 of the pole piece, and the walls 6" of ring 6 extend toward the yoke. Between the inner surface of the casing 1 and the coil 5 is a preformed shield 7 of insulating material having an aperture to accommodate the stem 3 of the pole piece. The shield closes the open side of the channel of the ring 6, and in a modification, FIGURE 2, the shield 7 is provided with integral inwardly directed flanges 7 fitting within the channel 6 adjacent the pole piece. These flanges facilitate assembly which is effected by introducing the ring, coil, and shield onto the stem of the pole piece, and subsequently assembling the latter to the casing.

Having thus described my invention what I claim as new and desire to secure by Letters Patent is:

1. Means for insulating the field :coi-l electrically from a pole piece having a head thereon and yoke of a dynamoelectric machine of the kind specified comprising a preformed ring of insulating material, said ring having a channel-sh-aped cross-section embracing the coil, with the base portion of said ring disposed against the head on? the pole piece and the walls of said ring extending towards the yoke, and a preformed apertured shield of insulating material lying against the internal periphery of the yoke to close the open side of the channel-shaped ring.

2. Means as claimed in claim 1 in which said shield is provided with integral inwardly directed flanges which in use fit within the channel of the ring.

References Cited UNITED STATES PATENTS 2,764,802 10/1956 Feiertag 310258 MILTON 0. HIRSHFIELD, Primary Examiner. L. L. SMITH, Assistant Examiner. 

1. MEANS FOR INSULATING THE FIELD COIL ELECTRICALLY FROM A POLE PIECE HAVING A HEAD THEREON AND YOKE OF A DYNAMOELECTRIC MACHINE OF THE KIND SPECIFIED COMPRISING A PREFORMED RING OF INSULATING MATERIAL, SAID RING HAVING A CHANNEL-SHAPED CROSS-SECTION EMBRACING THE COIL, WITH THE BASE PORTION OF SAID RING DISPOSED AGAINST THE HEAD OF THE POLE PIECE AND THE WALLS OF SAID RING EXTENDING TOWARDS THE YOKE, AND A PREFORMED APERTURED SHIELD OF INSULATING MATERIAL LYING AGAINST THE INTERNAL PERIPHERY OF THE YOKE TO CLOSE THE OPEN SIDE OF THE CHANNEL-SHAPED RING. 